Optical biosensor for detecting a blood cancer biomarker
doi:10.1038/nindia.2018.96 Published online 29 July 2018
A carbon-nanotube-based optical biosensor can detect a specific protein found on the membrane of chronic myeloid leukaemia cells, according to a new study1. This sensor is extremely sensitive and it allows non-invasive diagnosis of the deadly blood cancer.
Current techniques for detecting blood cancers are complex and expensive. They are not sensitive and often involve painful invasive procedures.
In search of a simple and non-invasive method, an international research team, including scientists from the Jamia Millia Islamia and Delhi University in New Delhi, India, made the sensor by using modified carbon nanotubes. They attached specific antibodies to the surface of the nanotube, which can bind to a protein expressed on the cell membrane of the blood cancer cells.
The sensor was exposed to different concentrations of the blood cancer cells in the presence of laser light. When the antibodies on the sensor surface captured the cancer cells, the sensor displayed a drop in light-induced current.
When the concentration of the cancer cells increased, there were a greater number of the cells bound to the surface of the sensor. The tiny cells blocked the electron transport in the sensor, increasing its resistance. This, in turn, decreased the current in the sensor, signalling the presence of the cancer cells.
The sensor, capable of detecting as low as 27 cancer cells in one millilitre of clinical sample, is less prone to contamination and human error — unlike the conventional techniques, the researchers say.
1. Gulati, P. et al. Leukemia biomarker detection by using photoconductive response of CNT electrode: analysis of sensing mechanism based on charge transfer induced Fermi level fluctuation. Sensor. Actuator. B. Chem. 270, 45-55 (2018)